The present invention is related to a damping/muffling structure for electroluminescent cell in which specific damping material is respectively painted near the light-emitting layer which is the vibration source so as to reduce or eliminate the vibration of the light-emitting layer produced when the light-emitting layer is driven and thus reduce or eliminate noise.
A conventional electroluminescent cell (EL cell) is a thin sheet which mainly serves as a back light element applied to PDA, mobile phone, etc. FIGS. 1 and 2 show the structure of a conventional EL cell. The EL cell is a thin sheet sequentially including a transparent substrate layer 11, a front electrode layer (ITO) 12, a light-emitting layer 13, an inductive layer 14, a back electrode layer 15 and an insulating packaging layer 16 attaching thereto. The front electrode layer 12 and the back electrode layer 15 are given an AC voltage, whereby the light-emitting layer 13 of the EL cell can provide a light-emitting effect. In order to enhance the waterproof ability of the EL cell, a waterproof layer 17 is attached to each of the outer faces of the EL cell as shown in FIG. 3.
The EL cell necessitates the AC voltage for driving the light-emitting layer 13 to light up. However, when driven by the AC voltage, the light-emitting particles in the light-emitting layer 13 will be energized to vibrate. Accordingly, the EL cell itself will vibrate and emit noise. Therefore, the quality of use of the EL cell is affected.
In order to solve the problem of noise, a backing is generally employed to increase the thickness of the EL cell. Alternatively, a sound-absorbing sheet is attached to the back of the EL cell. Still alternatively, the main body of the EL cell is solidly attached to the circuit board. Still alternatively, by means of dimension escape, the noise is reduced.
However, with respect to the EL back light cell used in PDA or mobile phone, the thickness specification is limited when designed. Therefore, the backing or sound-absorbing sheet. attaching to the back of the EL cell may lead to problem of excessive thickness. In the case that the EL back light cell is solidly attached to the circuit, over 60% noise is eliminated. However, it is hard to assemble the modules and the double-face adhesive leads to additional cost.
It is therefore a primary object of the present invention to provide a damping/muffling structure for electroluminescent cell. A damping layer is additionally integrally connected with the electroluminescent cell. The damping layer is able to truly provide a damping effect. This solves the problem of noise resulting from vibration of the EL cell itself when driven by AC voltage and ensures quality of use of the EL cell.
According to the above object, the damping/muffling structure for electroluminescent cell of the present invention includes a front electrode layer on which a light-emitting layer composed of a number of light-emitting particles is overlaid. An inductive layer is overlaid on the light-emitting layer. A back electrode layer is overlaid on the inductive layer. The back electrode layer is surrounded by an insulating packaging layer. A damping layer is integrally connected with the electroluminescent cell. The damping layer is composed of numerous damping molecules with high damping characteristic. By means of AC current of the front electrode layer and the back electrode layer, the light-emitting layer is driven to emit light and at this time the light-emitting particles are energized and vibrated. A friction is created between the damping molecules of the damping layer. The heat generated due to the friction can be dissipated.
The present invention can be best understood through the following description and accompanying drawings wherein: